One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,3)(4,7,8,6)(9,10,14,12)(11,16,13,15)(17,18,20,22)(19,21,23,24)(25,26,30,31)(27,32,33,28)(29,34,38,39)(35,37,40,36)(1,2,5,3)(4,7,8,6)(9,10,14,12)(11,15,13,16)(19,23)(21,24)(26,31)(27,33)(34,39)(35,40)(2,3)(6,7)(9,11,14,13)(10,15,12,16)(17,19)(18,21)(20,23)(22,24)(25,27)(26,32)(28,31)(29,35)(30,33)(34,37)(36,39)(38,40)(1,3,5,2)(4,7,8,6)(9,12,14,10)(11,15,13,16)(17,18)(19,21)(20,22)(23,24)(25,28,30,32)(26,33,31,27)(29,37,38,36)(34,35,39,40)(1,4,5,8)(2,6,3,7)(9,13,14,11)(10,15,12,16)(17,18)(19,21)(20,22)(23,24)(25,29,30,38)(26,34,31,39)(27,35,33,40)(28,36,32,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.